CARINA oxygen data in the Atlantic Ocean

[摘要] In the CARINA (Carbon dioxide in the Atlantic Ocean) project, a new dataset with many previously unpublishedhydrographic data from the Atlantic, Arctic and Southern Ocean was assembledand subjected to careful quality control (QC) procedures. Here, wepresent the dissolved oxygen measurements in the Atlantic region of thedataset and describe in detail the secondary QC procedures that aim toensure that the data are internally consistent. This is achieved by a cross-overanalysis, i.e. the comparison of deep ocean data at places that were sampledby different cruises at different times. Initial adjustments to theindividual cruises were then determined by an inverse procedure that computesa set of adjustments that requires the minimum amount of adjustment and atthe same time reduces the offsets in an optimal manner. The initialadjustments were then reviewed by the CARINA members, and only those thatpassed the following two criteria were adopted: (i) the region is not subject tosubstantial temporal variability, and (ii) the adjustment must be based on atleast three stations from each cruise. No adjustment was recommended forcruises that did not fit these criteria. The final CARINA-Oxygen dataset has103414 oxygen samples from 9491 stations obtained during 98 cruises coveringthree decades. The sampling density of the oxygen data is particularly goodin the North Atlantic north of about 40° N especially after 1987. Incontrast, the sample density in the South Atlantic is much lower. Somecruises appear to have poor data quality, and were subsequently omitted fromthe adjusted dataset. Of the data included in the adjusted dataset, 20%were adjusted with a mean adjustment of 2%. Due to the achieved internal consistency,the resulting product is well suited to produce an improved climatology or to study long-termchanges in the oxygen content of the ocean. However, the adjusted dataset is not necessarilybetter suited than the unadjusted data to address questions that require a high level of accuracy,such as the computation of the saturation state.

[学科分类] 天文学(综合)